sql - sql查询查找哪个国家的供应商和客户数量最多

Question

客户表列：

客户 ID 公司名称 联系人姓名 联系人职位 地址 城市 地区 邮政编码 国家 电话 传真

供应商表列：

供应商 ID 公司名称 联系人姓名 联系人职位 地址 城市 地区 邮政编码 国家 电话 传真 主页

从这些表中我们如何找到“哪个国家的供应商和客户数量最多......？” 我需要查询上述问题....？请回答我任何人......！

Answer 1

要获得单个国家/地区作为单个值包含在两个表中的最大次数，请将它们合并，然后将它们分组：

 select top 1 x.Country
 from (
   select Country from Customer
   union all
   select Country from Supplier) x
 group by x.Country
 order by count(1) desc

---

编辑：或者，您可以将两个表分别分组，然后将它们完全外部连接在一起，并添加匹配的术语（请记住处理null来自仅位于两个列表之一中的国家的 s ）：

select top 1 ISNULL(x.Country, y.Country) as [Country]
from (
  select Country, COUNT(1) as [Count] from Customers
  group by Country) x
full outer join (
  select Country, COUNT(1) as [Count] from Suppliers
  group by Country) y
on x.Country = y.Country
order by ISNULL(x.[Count], 0) + ISNULL(y.[Count], 0) desc

Answer 2

SQL 服务器语法

最大客户数

select Country from (
(with cte as (select Country,COUNT(*) cnt
from Customer
group by Country)
select Country,Rank() over (order by cnt desc) row_num from cte)a
where a.row_num=1

最大供应商数量

select Country from (
(with cte as (select Country,COUNT(*) cnt
from suppliers
group by Country)
select Country,Rank() over (order by cnt desc) row_num from cte)a
where a.row_num=1

Answer 3

SELECT a.country AS MaxCustomers, b.country AS MaxSuppliers
FROM
(
    SELECT TOP 1 country
    FROM customers
    GROUP BY country
    ORDER BY COUNT(*) DESC
) a
CROSS JOIN
(
    SELECT TOP 1 country
    FROM suppliers
    GROUP BY country
    ORDER BY COUNT(*) DESC
) b

应该输出如下内容：

MaxCustomers    |    MaxSuppliers
---------------------------------
USA             |    Japan